1. Field of the Invention
This invention relates to an amphiphilic high polymer, in particular, a modified amphiphilic high polymer which can be formed into film by Langmuir-Blodgett technique, and a process for producing the same.
2. Description of the Prior Art
It was found by Langmuir and Blodgett in 1930s that fatty acids having ca. 16 to 22 carbon atoms can form a monomolecular film on the surface of water and such a film can be built up or laminated on a substrate. However, it is only recent years that investigation of their technical application was started.
Outline of investigations hitherto made has been reviewed in "Kotai Butsuri (Physics of Solids)," 17 (12), p.45 (1982); "Thin Solid Film," 68, No. 1 (1980); ibid., 99, Nos. 1, 2 and 3 (1983); G. L. Gains, "Insoluble Monolayers at Liquid-gas Interface," Intersciene Publishers, N.Y. (1966); etc. However, conventional Langmuir-Blodgett films (hereinafter referred to as "LB film") of saturated straight chain carboxylic acids are not satisfactory in such points as heat resistance and mechanical strength and, therefore, could not be put into practical use as they are.
In order to rectify the above disadvantages, investigation have been made on polymetric films of saturated fatty acids, such as .omega.-tricosenic acid, .omega.-heptadecenic acid and .alpha.-octadecylacrylic acid; and unsaturated esters of fatty acids, such as vinyl stearate, octadecyl acrylate; as well as derivatives of diacetylene. Those films, however, are not sufficiently heat-resistant and have only poor electrical properties. It is also known that some hydrophilic group-containing polymers, such as polyacrylic acids, polyvinyl alcohols, polyethyl acrylates and polypeptides, also have film-forming properties. However, none of them are suited as a material for LB films, and no investigations have been made on modification of polymers to be used, in particular, as a material for LB films.
On the other hand, heat-resistant films have been produced from polyimides. However, polyimide films prepared by the spin coat method or the like usually have a thickness greater than 1 .mu.m, or at best 1,000 .ANG.. It is therefore very difficult to produce a heat-resistant film having a thickness of 1,000 .ANG. or less and, at the same time, free from pin holes.